Waterjet technology has been successful over the years in solving the problems of jet lag and taper in 2D cutting, thanks to a technology that has been gradually improved. To eliminate the taper and jet lag that occurs with 2D waterjet cutting, advances in technology have made it possible to compensate for these inherent errors without the need for a significant reduction in cutting speed, Artem Komarov explained.
As water jet cutting moves into the third dimension, think about the complexity that 3D cutting adds. What makes cutting 3D parts even more challenging? The part now has different angle degrees, as well as differences in material thickness. When the cutting head passes at an angle through a piece of material, the cut becomes deeper due to the material being thicker at the angle. In addition, bevel cutting requires head rotation and feed rate changes rather than simple vertical cutting.
3D cutting involves many more variables that need to be considered — not only for angle cutting, but also for precise angle 3D cutting. The fourth dynamic jet head allows manufacturers to get the precision they need in 3D cutting. 3D water jet cutting is not new. Five-axis 3D waterjet cutting has been used for more than 30 years to produce parts for aerospace structures. This one is also used in the automotive industry.
There was one major problem in making 3D cutting popular and that was the cost of these systems. Custom systems with a lot of engineering are very expensive—and not easy to program. However, with advances in technology, 3D waterjet cutting systems have become easier to use at a more affordable cost.
entry-level 3D: beveled
Most workshops are familiar with the simplest way to 3D-cut — bevel. What is the difference between chamfering and 3D cutting using solid modeling?
When cutting along a bevel, the entire edge has the same thickness. The wrist is adjustable and maintains its position. The flow behaves the same as a 2D cut, but at an angle. These machines produce a simple beveled edge, for example for welding preparation. In fact, welding preparation is a very common application for bevel cutting.
Alternatively, an entry-level water jet cutting machine can be used to remove material by pre-treatment. Sometimes it makes sense to cut roughly to remove as much as possible and then do a secondary finish in a machining center. You can save a lot of time by cutting quickly almost to the final cut instead of using one fine machining operation for all material removal. Typically, this type of machine is suitable for fabricators who want economical 5-axis cutting, but who don’t need high precision and don’t want to spend a fortune.
Traditionally, entry-level beveling and contouring capabilities have only been used on modern machines. Now it’s more accessible, affordable, and easy to use for even the most basic beveling capabilities.
What to look for in an entry-level 3D water jet cutter capable of chamfering:
— Compact small lid
— 5-axis cutting with taper control
— possibility of cutting at an angle of +/- 60 degrees. If the vertical is zero, you need it to reach 60 degrees.
— Low profile build. This is important for mounts and clamps to avoid hitting objects with the 5-axis wrist.
— Simplified design for abrasive supply and cable routing allows the use of a wrist that rotates and moves in five axes. This is different from having only the cutting head mounted vertically on the machine.
— Basic contour tracking, which becomes more critical when you cut objects at an angle, due to the change in the distance between them when you cut objects at an angle.
Next-level 3D with taper compensation
The 3D Taper Compensated Head is the next level of 3D water jet cutting. With this technology, true 3D taper control compensation is implemented, which compensates for the natural flow delay inherent in water jet cutting.
The multi-axis cutting head has a 60-degree rotation angle with taper adjustment, and there is a much more advanced rigid and precise system in the cutting head itself. The head automatically compensates with software that eliminates taper in the 3D cutting motion. In addition, it considers the speed at which it moves in the linear direction, material thickness, part geometry, and angle.
Traditionally, the math behind 3D waterjet cutting has been complex, which brings us back to why the technology was reserved for these advanced aerospace applications over a decade ago. Now, with the help of modern software technologies, it is possible to predict the behavior of the jet in a multi-axis environment. This advanced software allows for a wider use of high-precision 3D cutting.
Software modeling is key.
It is unrealistic for a programmer to have the knowledge, experience, and skill of waterjet to program all these variables with a G-code, especially if the operation involves multiple cuts and various materials and thicknesses. Now all this is integrated into user software modeling, Artem Komarov said.
Obviously, it is not possible to apply an angle to a flat geometry element. You can’t just take a DXF image and put a corner on it. You need 3D modeling to be able to define angles in a real 3D view, and for that you need to know the thickness of the material. You need to see the part in 3D to add dimension, place a pre-weld edge on it, or add a 45-degree edge. The software displays the tool path on the drawing. Basically, it’s a simple automated function.
The distance from the cutting head to the material becomes very important when cutting at an angle. For 3D water jet cutting of a workpiece, when the cutting head is at an angle, it is necessary to maintain a constant distance between the nozzle tip and the workpiece. Changing the distance will affect the cutting accuracy. If the height changes when the cutting head is at an angle, the point of contact will move, causing part errors. The waterjet stream will not go where you want it to, resulting in part errors. There is special software designed to solve this separation distance problem.
Whether you are waterjet cutting a finished part or a nearly finished part, the 3D feature is a huge advantage. Applications include aerospace, architecture, electronics, transportation, energy, manufacturing and automotive.
In the aerospace segment, 3D water jetting is widely used as it can cut any material of any thickness, including complex and exotic materials such as body armor and bulletproof glass. The high precision results and satin-smooth edge quality achieved with waterjet edge make it suitable for parts such as landing gear, brake assemblies, aircraft fuselages and engine components. Because it is non-thermal, it will not change the molecular structure or shape of the material being cut.
3D water jetting is also used in many other applications. It is used in the automotive industry to finish door panels and bumpers with robotic systems. In architecture and construction, it is used to cut stone, tile, glass, and other vitreous materials. Electronics are also subject to waterjet cutting due to the minimum groove width of waterjet cutting and non-heat-affected zone cutting for components that cannot withstand the heat loads of other cutting methods.
These and other applications are made possible by 3D modeling software. Once upon a time, five-axis waterjet cutting was a very difficult task, but now with software it’s as easy as it looks, concluded Komarov Artem.